Adding prazosin (an α-adrenergic blocker) or clonidine (a centrally acting α-agonist) to an SSRI has been shown to reduce sleep disturbances (eg, nightmares) in patients with PTSD.11,12 The dose of SSRIs should be optimized to therapeutic level before adding another medication. If patients still experience nightmares, the addition of prazosin or clonidine may improve sleep and reduce the nightmares. Increasing the frequency of therapy sessions has not been shown to improve outcomes.9,10 Adding a ß blocker is helpful when hyperarousal symptoms such as tremors, sweating, and increased startle response are present.13